The present invention relates to a thrombolytic drug which can be orally administered. In particular, the present invention relates to a thrombolytic drug having a function of accelerating the release of a tissue plasminogen activator (t-PA) in vascular endothelial cells, while exerting substantially no effect on the release of type-1 plasminogen activator inhibitor (PAI-1) which deactivates t-PA or reducing the release thereof.
A thrombosis caused by the blood coagulation in the bodies causes serious diseases such as hypertension, stroke and myocardial infarction. Usually drugs affecting the blood such as antiplatelet drugs, anticoagulant drugs and thrombolytic drugs are used for these diseases. Although the antiplatelet drugs and anticoagulant drugs are effective in preventing the formation of thrombi, the effects of them on the patients having the thrombi already formed are only slight and an early fibrinolytic therapy with a thrombolytic drug is necessitated. In the fibrinolytic therapy, a factor capable of developing a fibrinolytic reaction is given in order to dissolve and thereby to remove the thrombi. As the thrombolytic agents, those obtained from fibrinolytic substances per se such as tissue plasminogen activators, urokinase, streptokinase and prourokinase by a gene recombination technique have been used hitherto. However, such a thrombolytic agent must be directly applied to a location of the thrombus formation or the blood vessel. Under these circumstances, the development of a thrombolytic drug which can be orally administered has been demanded.